This invention relates to an improved process for the polymerization of epoxides to form granular polymer products.
Granular epoxide polymer products are useful as flocculants, thickeners, gels, friction reduction agents and dispersants.
Methods of polymerizing epoxides to form solid polymer particles are known. For example, U.S. Pat. No. 2,941,963 describes a process of polymerizing ethylene oxide to form "granular polymer product" by carrying out the polymerization in a solvent for ethylene oxide in which the polymer is insoluble (suspension polymerization). The polymerization reaction is catalyzed by a basic catalyst such as a hexammoninate, a decomposition product thereof or an alkaline earth metal amide.
U.S. Pat. No. 4,460,703 describes a novel catalyst for epoxide polymerization. This catalyst comprises the reaction product of: (1) a trialkylaluminum compound, (2) phenothiazine, (3) 1,4-dioxane or tetrahydrofuran, (4) water, and (5) acetylacetone. This catalyst demonstrates improved rates of polymerization for epoxide homopolymers and copolymers.
Unfortunately, the catalysis system of U.S. Pat. No. 4,460,703 cannot be used in the suspension polymerization of U.S. Pat. No. 2,941,963. When attempted, a solid hard polymer which coats the reaction vessel is formed rather than a granular product.
Therefore, it would be desirable to have a method of producing granular polymer products that cannot be formed via conventional suspension polymerization methods.